Having trouble with the bay12games.com domain. But it's not a Bay12 issue so far as I can tell, so putting it here to get ideas...
Compare and contrast:
1) Old Laptop (Wifi connection to home ISP router): bay12games.com (with www. or dffd. subdomains) redirected to my ISP's default Error Replacement Service (looks like an unbranded Google results for "what they they I want to connect to", mostly Paid Ads but with bay12games, bay12forums and the Patreon/bay12 pages in there for good measure. Confirmed through the likes of Ping and Tracert that traffic goes to this service. Even after I 'activated' the ISP's opt-out, which quite famously does not opt out.
2) Old PC (wired connection to home ISP router): no ad-jacking DNS, but this may be because I changed the default DNS used to something that helped a different issue. However, the browser (Firefox) nw gives the old "did you mistype/miss out the www. part?" message and a Try Again button that does nothing more, so obviously somewhere in the upstream DNS I still get something invalid.
3) Tablet, with Mobile Internet or Wifi to the same router: bay12games.com works as it always has, on either mobile (different ISP, not even one under the same umbrella due to merger/corporate assocation) or wifi. Not sure if this is because it got the working DNS info while on mobile ISP and continues to use it successfully over the home ISP, because I don't have easy access to any of the same tools for which I discovered such inner details of the Error Replacement as I have already found.
No problems with any other domains (bay12forums included) but the two offshoots bay12games I tried. I would guess (without easy tracking other than resorting to third party tools) that dffd is not even hosted on the same hardware, so why both would (initially) even return an NXDOMAIN, for it to then selectively replace with the 'helpful' URL hijack on just the one machine that does that I have no idea.
The ISP involved is notoriously bad on support (via all lines of communication). I could pester them by phone, email, livetalk, at least two different support/community forums, etc, but noting recent traffic discussing the inability to opt-out with the opt-out (and unrelated VPN troubles that this is causing, which other are having) I'm wondering what things I might have overlooked that I can test and/or tweak.
(I could perhaps (re)change the DNS being called upon, or something more drastic, but I don't want to do that lightly. Not for just bay12games access, which I don't specifically need right now and I only discovered when I got rerouted after having not typed the /smf/ ending to the bat12forums URL, in haste. I can review the rest of the site on the tablet, and have been, and there's nothing I currently need to download to Windows.)
If I was free to move equipment to a different place, I might take the laptop over to try to get through a different ISP (from the current location or mobile access) and do a suitable /refresh on the DNS info but, right without the ability to do this anywhere but its current locale, it seems it would just refail the same apart from any redirect element. Can't work out how to possibly 'break' the tablet in the same way (if it is only true right now because it recalls a working server resolution, not yet deemed needing auto /refresh) and don't much care to.
Do I make sense? Maybe not perfectly, but it's a puzzle, in case anyone wants to help me solve it before I get around to doing anything too drastic myself, or it resolves itself spontaneously.